var year = prompt("请输入年份");
var  month  = prompt("请输入月份");

years = Number(year);
month = Number(month);


//1980年有多少天
//365 366
function runNian(year) {
    if (year % 400 === 0 || (year % 4 === 0 &&year % 100 !==0)){
        return true;
    }else {
        return false;
    }
}

var days = 0;
//1980年全年 +到2018年全年
for (var i = 1980; i<year; i++){
    if (runNian(i)){
        days +=366;
    }else {
        days+=365;
    }
}

//1月 -4月全月一共有多少天
for (var  k=1;k<month;k++){
    switch (k){
        case 1:
            days +=31;
            break;
        case 2:
            if (runNian(year)){
                days +=29;
            }else {
                days +=28;
            }
            break;
        case 3:
            days +=31;
            break;
        case 4:
            days +=30;
            break;
        case 5:
            days +=31;
            break;
        case 6:
            days +=30;
            break;
        case 7:
            days +=31;
            break;
        case 8:
            days +=31;
            break;
        case 9:
            days +=30;
            break;
        case 10:
            days +=31;
            break;
        case 11:
            days += 30;
            break;
        case 12:
            days +=31;
            break;
    }
}

//因为1980年的一月一日前面有2个空位所以加2
days +=2;
console.log(days);

//算出起始位置
var start = days % 7;
console.log(start);

//选上这个标签
var day = document.querySelector("#day");

//上一个月一共有多少天？
var prevDay =0;
//找到上一个月多少天
switch (month - 1){
    case 0:
        prevDay +=31;
        break;
    case 1:
        prevDay +=31;
        break;
    case 2:
        if (runNian(year)){
            prevDay +=29;
        }else {
            prevDay +=28;
        }
        break;
    case 3:
        prevDay +=31;
        break;
    case 4:
        prevDay +=30;
        break;
    case 5:
        prevDay +=31;
        break;
    case 6:
        prevDay +=30;
        break;
    case 7:
        prevDay +=31;
        break;
    case 8:
        prevDay +=31;
        break;
    case 9:
        prevDay +=30;
        break;
    case 10:
        prevDay +=31;
        break;
    case 11:
        prevDay += 30;
        break;
    case 12:
        prevDay +=31;
        break;
}


//本月一共有多少天？
var thisDay = 0;
//找到上一个月多少天
switch (month){
    case 1:
        thisDay +=31;
        break;
    case 2:
        if (runNian(year)){
            days +=29;
        }else {
            days +=28;
        }
        break;
    case 3:
        thisDay +=31;
        break;
    case 4:
        thisDay +=30;
        break;
    case 5:
        thisDay +=31;
        break;
    case 6:
        thisDay +=30;
        break;
    case 7:
        thisDay +=31;
        break;
    case 8:
        thisDay +=31;
        break;
    case 9:
        thisDay +=30;
        break;
    case 10:
        thisDay +=31;
        break;
    case 11:
        thisDay += 30;
        break;
    case 12:
        thisDay +=31;
        break;
}


for(var j =prevDay - start +1;j<=prevDay;j++){
    day.innerHTML += '<span class="h">' +j+'</span>';
}

//取到今天
var d = new  Date().getDate();
for (var s=1; s<=thisDay; s++){
    if(s==d){
        day.innerHTML += '<span class="today">' +s+'</span>';
    }else {
        day.innerHTML +='<span>' +s+'</span>';
    }
}

//总空位是42位
var num = 42;
//算出还剩几个位置
var endDay = num - start - thisDay;

for(var e=1; e<=endDay;e++){
    day.innerHTML += '<span class="h">' +e+'</span>';
}

//赋值标题的年和月

document.querySelector("#nian").innerHTML = year;
document.querySelector("#yue").innerHTML = month;